Epoxy is for structural repair; it bonds concrete back together but is rigid. Polyurethane is for waterproofing; it expands to fill the crack and remains flexible as the house shifts. At Basement Expert, we analyze the crack first. If the wall is moving, we use carbon fiber for strength and polyurethane for the seal. Using the wrong material is why many “cheap” repairs fail within a year. We use the right technical material for your specific site conditions.